Pressure in Electrical Conduction and Decomposition, 435 



from the sheet itself or from the portion of the sheet which 

 coincides sensibly with the tangent plane at the place consi- 

 dered, or from an infinite plane sheet coinciding with that 

 tangent plane. This is on the assumption that the part of 

 the sheet which coincides sensibly with the tangent plane is 

 of large dimensions compared with the thickness of the 

 dielectric, i. e. that the latter is small compared with any 

 radius of curvature of the sheet. 



The result obtained therefore holds for curved double sheets 

 as well as plane ones. 



Now, if a curved sheet be under a uniform surface-tension 

 T, it is well known that the stress experienced by any element 

 SS of its surface is along the normal, and equal to 



AEi + bJ 



SS, 



R 1? R 2 being the principal radii of curvature where SS is 

 situated. When we apply this to the electrical double layer, 

 we obtain the same result as comes from the direct expression, 

 on Green's theory, of the force exerted by the electrical system 

 on the two charged faces which belong to the element SS. 



For a single curved electrified layer of finite dimensions, 

 open or closed, the surface-tension is different at different 

 points, and at the same point across different lines on the sur- 

 face ; except in the case of an electrified spherical sheet, in 

 w 7 hich it is easily seen to be constant and equal to — TTp 2 a, 

 w T here a is the radius of the sphere. 

 September 11, 1885. 



L. On the Influence of Pressure on certain cases of Electrical 

 Conduction and Decomposition. By J. W. Clark, Assistant 

 Professor of Physics in University College, Liverpool* . 



AS the subject of electrolysis is to be brought prominently 

 before the next Meeting of the British Association, the 

 following short outline of an investigation, commenced some 

 years ago, may not be without interest at the present time. 



The subject properly divides itself into three branches, viz. : — 

 the influence of pressure on the electrical conduction and 

 decomposition of — 



I. Dilute sulphuric acid (products of electrolysis occupying 

 much greater volume than when combined to form the elec- 

 trolyte). 



II. A solution of (e. g.) CuS0 4 (products of electrolysis 



* Communicated by the Author. 



